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At least 145 records · Page 8Linked to original sources
PubMed1989

Membrane fluidity of guinea pig lymphocytes and the dysfunction of the respiratory airway and lymphocyte beta-adrenergic systems of the guinea pig.

The beta-adrenergic receptor responsiveness of isolated guinea pig tracheal spirals can be negatively affected by intraperitoneal administration of the Gram-negative bacterium Haemophilus influenzae, four days prior to the experiment. The reduction in tracheal relaxation is accompanied by a decrease in beta-adrenergic receptor binding sites in splenic lymphocyte membranes and by a decrease in the fluidity of these membranes. The H. influenzae-induced dysfunction of both the respiratory airway and lymphocyte beta-adrenergic systems can be mimicked by modulating the amount of linoleic acid in the diet. This linoleic acid induced dysfunction of the beta-adrenergic system is also accompanied by a decrease in the plasma membrane fluidity of the splenic lymphocyte membranes of the guinea pigs. The role for plasma membrane fluidity in asthma is discussed in relation to current concepts for atopy.

Animals↗
PubMedDate not supplied

A novel radioimmunoassay for neuromedin K. I. Absence of neuromedin K-like immunoreactivity in guinea pig ileum and urinary bladder. II. Heterogeneity of tachykinins in guinea pig tissues.

A novel and highly specific radioimmunoassay for the tachykinin peptide neuromedin K (NMK, also known as neurokinin beta, neurokinin B) has been developed and used to determine the distribution of this peptide in extracts of guinea pig tissues. In addition to immunoreactive components coeluting with the 3 mammalian tachykinins, substance P (SP), substance K (SK) and NMK, analyses using reverse-phase HPLC revealed immunoreactive peaks coeluting with the C-terminal octapeptide of SK (SK-(3-10], an N-terminally extended form of SK (gamma-preprotachykinin-(72-92)amide), and a yet unidentified peak eluting before NMK in the extracts of guinea pig brain and spinal cord. In contrast to the other tachykinins, SP and SK, which were present in high concentrations in extracts of all peripheral and central tissues examined, NMK-like immunoreactivity was detected only in extracts of central tissues. NMK-like immunoreactivity was not detected in extracts of terminal ileum and urinary bladder.

Animals↗
PubMedDate not supplied

Effects of guinea pig vasoactive intestinal peptide on the isolated perfused guinea pig heart.

The pharmacological effects of guinea pig vasoactive intestinal peptide (VIP) were studied in isolated perfused guinea pig hearts. Bolus injections of VIP produced a dose-dependent tachycardia that was not affected by atenolol. A decrease in amplitude of ventricular contractions occurred in response to all doses of VIP. This response was preceded by a small increase in amplitude in 3 of 6 hearts at the highest dose. VIP produced a decrease in perfusion pressure which was prominent after coronary tone was elevated with [Arg8]-vasopressin. The present findings support speculation that VIP may have a role in the regulation of heart rate and coronary blood flow.

Animals↗
PubMedDate not supplied

Porcine VIP is more potent than guinea pig VIP in relaxing the guinea pig uterine artery.

The vasodilator potency of guinea pig VIP (gp VIP) on the guinea pig uterine artery was compared with the potency of porcine VIP (p VIP), which differs in amino acid sequence at four locations. When antioxidants were not used, the two peptides were approximately equipotent in causing relaxation of precontracted vessel segments. Use of the antioxidants ascorbic acid and dithiothreitol resulted in significantly increased potency of both peptides. Porcine VIP was 15 times more potent than gp VIP synthesized by the same method (tBoc), and gp VIP synthesized by tBoc methodology was 2 times more potent than gp VIP synthesized by Fmoc methodology. Therefore, care should be taken in the choice and handling of synthetic peptides when aiming to mimic actions of endogenous peptides.

Animals↗
PubMed1987

Partial agonists at guinea-pig atrial beta-adrenoceptors display relaxation responses in the guinea-pig ileum independent of beta-adrenoceptor stimulation.

The beta-adrenoceptor mediated responses of oxyfedrine, ritodrine, tazolol, prenalterol, salbutamol and carteolol were examined on guinea-pig left and right atrial and ileal preparations. All agonists tested in left and right atrial preparations were partial agonists relative to isoprenaline. All agonists with the exception of salbutamol, which appeared a full agonist, produced relaxation responses significantly greater than isoprenaline in ileal preparations. The response to ritodrine in the ileum was not influenced by practolol, in a concentration which antagonized the responses of ritodrine in the right atria. The response of the ileum to beta-adrenoceptor antagonists of varying lipophyllicity was examined. Propranolol and pindolol both produced relaxation responses relative to their lipophyllicities. No relaxation was observed to atenolol, which exhibits very low lipophyllicity. It is concluded that beta-adrenoceptor agonists exhibit a substantial relaxation of guinea-pig ileum that is independent of beta-adrenoceptor stimulation.

Adrenergic beta-Agonists↗
PubMed1992

Li+ increases accumulation of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate in cholinergically stimulated brain cortex slices in guinea pig, mouse and rat. The increases require inositol supplementation in mouse and rat but not in guinea pig.

Li+, beginning at a concentration as low as 1 mM, produced a time- and dose-dependent increase in accumulation of [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4,5)P4 in acetylcholine (ACh)-stimulated guinea-pig brain cortex slices prelabelled with [3H]inositol and containing 1 mM-inositol in the final incubation period. Similar results were obtained by mass measurement of samples incubated with 10 mM-Li+ by using a receptor-binding assay, although the percentage stimulation of Ins(1,4,5)P3 accumulation by Li+ was somewhat less by this assay. The increase in accumulation of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 by Li+ was absolutely dependent on the presence of ACh. In the absence of added inositol, 1-5 mM-Li+ produced smaller increases in Ins(1,4,5)P3, but the Li(+)-dependent increase in Ins(1,3,4,5)P4 was not as affected by inositol omission. In previous studies with cholinergically stimulated rat and mouse brain cortex slices, Li+ inhibited accumulation of Ins(1,4,5)P3 in rat and inhibited Ins(1,3,4,5)P4 accumulation in rat and mouse [Batty & Nahorski (1987) Biochem. J. 247, 797-800; Whitworth & Kendall (1988) J. Neurochem. 51, 258-265]. We found that Li+ inhibited both Ins(1,4,5)P3 and Ins(1,3,4,5)P4 accumulation in these species, but we could reverse this inhibition by adding 10-30 mM-inositol; we then observed a Li(+)-induced increase in Ins(1,4,5)P3 and Ins(1,3,4,5)P4. The species differences observed in the absence of supplemented inositol were explained by the fact that a much higher concentration of inositol was required to bring the Li(+)-elevated levels of CDP-diacylglycerol (CDPDG) down to baseline in the rat and mouse. These data suggest that inositol is more rate-limiting for phosphatidylinositol synthesis in the presence of Li+ in rat and mouse, which can account for the previous reports of inhibition of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 accumulation by this ion in these species. Thus, in all species examined. Li+ could be shown to increase accumulation of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 in cholinergically stimulated brain cortex slices if the slices were supplemented with sufficient inositol to bring the Li(+)-elevated level of CDPDG down to near baseline, as seen in the absence of Li+. In guinea-pig brain cortex slices, increases in Ins(1,4,5)P3 and Ins(1,3,4,5)P4 accumulation could then be seen at Li+ concentrations as low as 1 mM, which falls within the therapeutic range of plasma concentrations in the treatment of manic-depressive disorders. These observations may have therapeutic implications.

Animals↗
PubMed1969

Transfer of responsiveness to hapten conjugates of poly-L-lysine and of a copolymer of L-glutamic acid and L-lysine to lethally irradiated nonresponder guinea pigs by bone marrow or lymph node and spleen cells from responder guinea pigs.

Hartley guinea pigs genetically unresponsive to hapten-PLL (poly-L-lysine) conjugates were lethally irradiated and given allogeneic bone marrow from Hartley responder animals. Many of the animals died of graft versus host disease before their response to 2,4-dinitrophenyl-PLL (DNP-PLL) could be measured. The immune response of the surviving recipient animals was evaluated by anti-DNP antibody production, development of delayed hypersensitivity to DNP-poly-L-lysine, as well as by lymph node cell stimulation in vitro by this antigen. 12 of 14 recipient animals thus treated made an immune response as measured by 2 of the 3 parameters. Strain 13 guinea pigs, genetically unable to respond immunologically to DNP-PLL and to DNP-GL (2,4-dinitrophenyl-L-glutamic acid L-lysine copolymer) were lethally irradiated and given bone marrow from (2 x 13) F(1) responder animals or strain 13 bone marrow and (2 x 13) F(1) lymph node and spleen cells. A high proportion of the animals survived this procedure; no evidence of graft versus host disease was observed. Three of three strain 13 animals irradiated and, given strain 13 bone marrow and (2 x 13) F(1) lymph node and spleen, and then immunized with DNP-PL, made a specific immune response. 7 of 10 irradiated strain 13 animals given strain 13 bone marrow and (2 x 13) F(1) lymph node and spleen made an immune response to DNP-GL. However, only one of six irradiated strain 13 animals made a vigorous immune response to DNP-GL after reconstitution with (2 x 13) F(1) bone marrow alone. The ability to transfer the immune response to PLL antigens from responder to nonresponder animals demonstrates unequivocally that the defect in the non-responder animals is immunological rather than due to some other type of non-immunological mechanism. The bone marrow contains all the immunological cells necessary for the expression of the PLL gene. However, the finding that (2 x 13) F(1) lymph node and spleen cells were more effective than (2 x 13)F(1) bone marrow cell populations (known to be a rich source of monocyte precursors) suggests that the cells in which the PLL gene function is expressed may be lymphocytes rather than monocytes and macrophages.

Animals↗
PubMed1953

Regression of transplanted lymphomas induced in vivo by means of normal guinea pig serum. I. Course of transplanted cancers of various kinds in mice and rats given guinea pig serum, horse serum, or rabbit serum.

In the experiments here described transplanted lymphomas of two kinds regularly regressed following repeated injections of normal guinea pig serum intraperitoneally into mice carrying them, the animals meanwhile remaining lively and devoid of signs of illness or wasting. The lymphomas of untreated control mice, by contrast, usually grew progressively and killed their hosts within 20 to 30 days, and the same was true of the growth of other mice given repeated injections of horse serum or rabbit serum. In similar experiments, the cells of a transplanted lymphosarcoma of rats were temporarily kept from proliferating by repeated intraperitoneal injections of guinea pig serum, though the cells of two transplanted mammary carcinomas of mice, and those of fibrosarcoma, grew unimpeded in hosts likewise treated. Additional experiments related to the phenomenon here described, and a discussion of the findings as a whole, are given in an associated paper.

Animals↗
PubMed1979

Target tissues associated with genital infection of female guinea pigs by the chlamydial agent of guinea pig inclusion conjunctivitis.

Female guinea pigs were experimentally infected in the genital tract with the strain of Chlamydia psittaci that causes guinea pig inclusion conjunctivitis. Chlamydiae were found frequently in superficial squamous epithelial cells of the exocervix, along with heavy involvement at the squamocolumnar junction. In this zone chlamydiae were observed in columnar cells, but inflammation and chlamydial inclusions were not observed in true endocervical epithelium. These observations were supported by results of immunofluorescence microscopy. Electron micrographs revealed typical chlamydiae within surface epithelial cells at the squamocolumnar junction; various stages of the growth cycle (elementary, reticulate, and intermediate bodies) were also present. Cytopathologic features were not remarkable, but peripheral distribution of organelles, rarefaction of the cytoplasm, and loss of microvilli were observed.

Animals↗
PubMed1979

Ultrastructural development of guinea pig cytomegalovirus in cultured guinea pig embryo cells.

The ultrastructural development of guinea pig cytomegalovirus (GPCMV) in guinea pig embryo cells was studied using electron microscopy. Tubular structures were found in nuclei of virus infected cells, followed by the appearance of intranuclear inclusions containing virus nucleocapsids. While some nucleocapsids were enveloped at the inner nuclear membrane, others were released into the cytoplasm where they were associated with, or within, dense matrix which was subsequently enveloped by cytoplasmic membranes to form enveloped dense virions. Dense bodies without virus capsids were formed in the cytoplasm and enveloped in a similar manner. An involvement of the nuclear pores in the release of unenveloped virus capsids from the nucleus to the cytoplasm was postulated. Evidence that the enveloped dense virions and dense bodies shared common envelope antigen(s) was obtained by immunoelectron microscopy. The similarities and differences in the ultrastructural development of GPCMV and other cytomegaloviruses are discussed.

Animals↗
PubMed1992

Purification and characterization of a binding protein related to the Z class of cytosolic proteins in guinea-pig liver cytosol (guinea-pig Z protein).

The purification and characterization of a low-molecular-mass binding protein from female guinea-pig liver cytosol is reported. Its molecular mass (14.4 kDa), amino acid composition, abundance and biological properties identify it as belonging to the Z class of liver cytosolic proteins [Levi, A.J., Gatmaitan, Z. & Arias, I.M. (1969) J. Clin. Invest. 48, 2956-2167]. Among the most important members of this class of proteins are the fatty-acid-binding proteins (FABPs) and the sterol carrier protein2 (SCP2). The guinea-pig Z protein (G-ZP) has some similarities in its amino acid composition and NH2-terminal sequence with those of the rat liver FABP, but its isoelectric point is basic (pI 8.85), like that of SCP2. We also examined its binding affinities for a number of ligands bound by these two proteins. The results show that the purified G-ZP binds dehydroepiandrosterone sulfate, estrone sulfate, oleic acid and cholesterol, but shows no affinity for free steroids such as estrone and DHEA. Thus it can be said that G-ZP has some characteristics of FABPs and some of SCP2 but seems, however, to be different from both these proteins. The purified G-ZP inhibits microsomal DHEA sulfate sulfatase activity in a mixed noncompetitive way. This protein could be involved in the transport and/or metabolism of sulfated steroids.

Amino Acid Sequence↗
PubMed1978

A comparison of the binding constant (KD) of 125I-labelled 3-(4-iodophenoxy)-1-isopropylamino-propan-2-ol obtained on beta-adrenoceptors in guinea-pig myocardial membranes, with its dissociation constants (KB) obtained on guinea-pig isolated atria and trachea.

The dissociation constant of binding (KD) of 125I-labelled 3-(4-iodophenoxy)-1-isoproplyaminopropan-2-ol (IIP) to guinea-pig myocardial membrane preparations was 2.2 x 10-8M. In pharmacological experiments with the non-labelled material and 60 min contact time, IIP produced a parallel shift in the orciprenaline concentration-response line on guinea-pig isolated tracheal and atrial preparations. The dissociation constant (KB) of IIP was 2.9 x 10-8M on atria (pA2 7.54) and 3.3 x 10-8M on trachea (pA2 7-48). These values indicate that IIP is not a selective beta-adrenoceptor blocking drug. In addition, agreement was found between the affinity constant of this antagonist for beta-adrenoceptors as determined by a direct binding study and an indirect pharmacological study.

Adrenergic beta-Antagonists↗
PubMed1978

Immunity to vaginal reinfection in female guinea pigs infected sexually with Chlamydia of guinea pig inclusion conjunctivitis.

Guinea pig boars were inoculated intraurethrally with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC). At the heights of their urethral infections, they were caged with sows in estrus. Whereas some of the sows had not been previously exposed to GPIC agent, others had received an intravaginal inoculation 5 to 8 weeks earlier. Those sows for which infected boars provided the first exposure were challenged by intravaginal inoculation 5 to 8 weeks later. Vaginal and conjunctival scrapings were taken regularly and stained for chlamydial inclusions. Titers of serum anti-GPIC antibodies and of vaginal secretory IgA anti-GPIC antibodies were determined by immunofluorescence. Our results show for the first time that a sexually acquired vaginal GPIC infection induces immunity to manual reinfection of the vagina. Because of the high incidence of secondary conjunctival infections among the vaginally infected sows, we could not provide a sound statistical basis for our tentative conclusion that manual infection of the vagina induces immunity to sexual reinfection. The results of our antibody titrations confirm previous work showing that vaginal GPIC infection induces formation of both serum antibody and vaginal secretory immunoglobulin A antibody.

Animals↗
PubMed1981

Cell-mediated and humoral immune responses to chlamydial antigens in guinea pigs infected ocularly with the agent of guinea pig inclusion conjunctivitis.

Cell-mediated immune response and humoral response to chlamydial antigens were investigated in guinea pigs infected with the agent of guinea pig inclusion conjunctivitis (GPIC). Pronounced cell-mediated immune response to the homologous antigen, as well as to two other chlamydial antigens, 6BC (Chlamydia psittaci) and LB-1 (C. trachomatis), occurred in all infected animals. Cell-mediated immune response to GPIC, and to a lesser extent to 6BC and LB-1 as well, was enhanced with time after infection even without the re-inoculation of the infectious agent. Extensive cross-reactions among the three chlamydial antigens during the cell-mediated immune response appeared to be due to shared species-specific and group-reactive antigens. Serum antibody response was pronounced and uniform to GPIC; it was less marked to 6BC and LB-1, with fewer cross-reactions than seen in tests for cell-mediated immunity.

Animals↗
PubMed1973

Experimental genital infection of male guinea pigs with the agent of guinea pig inclusion conjunctivitis and transmission to females.

Male guinea pigs were inoculated intraurethrally with the agent of guinea pig inclusion conjunctivitis (Gp-ic). Cytoplasmic inclusions were found in superficial epithelial cells of the urethra in smears and stained sections. Gp-ic antigen(s) was detected by immunofluorescent staining of sections. There was no marked urethral exudate, but many animals developed bullous lesions on the glans and the body of the penis and a severe inflammatory lesion of the hind leg. All males demonstrated an antibody response and most of them showed a positive skin test reaction. Venereal transmission to females of Gp-ic infection was shown to occur as determined by detection of inclusions in vaginal smears, antibody response, and positive skin tests.

Animals↗
PubMed1986

Susceptibility of fetal guinea pig brain cell cultures to replicating guinea pig cytomegalovirus infection is increased with increasing fetal age: infection of astrocytes.

Guinea pig brain cell cultures were established from fetuses at 25, 31, and 37 days of gestation (DG). After 7 days in vitro, the cultures were infected with guinea pig cytomegalovirus (GPCMV). Based on cytopathic effect, immunofluorescence staining for GPCMV by using virus-specific antiserum, and the amount of virus recovered, cultures established from fetuses at 25 DG were least susceptible to replicating infection, and cultures established from fetuses at 37 DG were most susceptible. Using cell-type-specific markers, it was determined that the increase in susceptibility to replicating infection paralleled an increase in the number of differentiated cells. Astrocytes were the most abundant cell type identified and were susceptible to replicating GPCMV infection, whereas neurons were not.

Animals↗
PubMed1986

Assessment of the cardiohemodynamic effects of ibopamine, an orally-active dopamine analogue, in the anesthetized open-chest guinea pig and the isolated guinea pig atria.

In the anesthetized open-chest guinea pig, ibopamine (10-300 micrograms/kg, i.v.), epinine (10-100 micrograms/kg, i.v.) and dopamine (10-300 micrograms/kg, i.v.) produced dose-related increases in heart rate (prevented by 20 micrograms/kg pindolol, i.v.), left ventricular dP/dt max and aortic flow. Ibopamine produced pressor effects (prevented by 0.5 mg/kg phentolamine, i.v.), while dopamine produced a slight depressor effect. A biphasic response (the pressor phase followed by a depressor) was observed after epinine, although the depressor phase was not significant. Calculated total peripheral resistance (TPR) tended to be increased after ibopamine and epinine (initial phase), while it was decreased after dopamine. Pindolol potentiated the increase in TPR produced by ibopamine and epinine, while the increase in TPR was converted to the decrease after phentolamine. Decreases in TPR produced by epinine and the highest dose of dopamine were inhibited by pindolol. In the isolated guinea pig atria, ibopamine (10(-6)-10(-4) M) increased the atrial rate and the developed tension in a concentration-related manner. The positive chronotropic and inotropic effects of ibopamine were of the same order as those of epinine.

Animals↗
PubMed1977

Studies of sperm antigenicity. 6. In vivo and in vitro cellular reactivity in guinea pigs sensitized with fractions of guinea pig spermatozoa.

Normal guinea pig spermatozoa cells were homogenized by a French pressure cell. Three soluble and three insoluble fractions were obtained by ultrascentrifugation and (emulsified in CFA) were used for guinea pig sensitization. The following were observed: 1) all fractions were immunogenic except one; 2) in vivo and in vitro delayed hypersensitivity was elicited in animals immunized with these fractions; 3) two distinctive histopathologic lesions were observed in the testes of sensitized animals: lesions of orchitis type developed in animals injected with some fractions. Other fractions induced lesions of aspermatogenic type. These results correlated well with delayed hypersensitivity results obtained by in vivo and in vitro tests. Although some other spermatozoal fractions did not cause severe changes in the testes. The lack of sperm accumulation in the epididymis was obvious.

Animals↗